Some Truths Are Hard To Define
by altschmerz
Summary: There are a number of theories, among members of the Dalton family tree, on how the young man they have concluded to be Jack's kid came to exist. There has to be an explanation, and since nobody met him until he was twenty, the explanation has to be good. (or, the one where jack finds out after five years of bringing mac to family reunions that his family thinks he has a son.)


_soooooo here it is. the most ridiculous idea i've ever had, sprung forth into a genuinely heartfelt 5k fic about family and the complicated definitions thereof, featuring the extended dalton clan, a rather unique case of mistaken identity, miraculously one one (1) hockey reference, and a csi easter egg for anyone who cares to find it._

 _please, drop me a line and let me know what you think! this was a labor of love that never would've seen the light of day if it weren't for the lovely folks over on tumblr, thank you all so much, and if you'd like to check out what i get up to over there, you can find me at altschmerzes! (title's from sleeping at last's song 'south')_

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There are a number of conflicting theories, among various and sundry members of the Dalton family tree, on how exactly the young blonde man they have concluded has to be Jack's kid came to be. Seeing as he can't have just sprung forth unto the earth fully formed, there has to be an explanation, and since nobody met him until he was out of high school, the explanation has to be something good. It's been a hotly debated topic since the first Annual Dalton Family Reunion Jack brought him to - always, of course, out of earshot of Jack, the kid in question, and Great-Aunt Lynette, who has made it very clear there are to be no impolite questions, given, "the poor boy is obviously in an uncomfortable enough position, and I don't want to hear about none of y'all saying anything _unkind_ to him."

The facts are these:

One: Jack, much beloved among the many Dalton cousins for his willingness to play games with the kids and his genuine interest in the answer when he asked you questions about your life, never married or had kids.

Two: Five years ago, Jack showed up to the annual family reunion with a blonde kid in tow, introduced him as Mac, and provided absolutely no explanation as to who he was.

Three: Mac is a certified genius recruited by a think tank, where he often works with Jack, who is some kind of security consultant.

Four: Judging by the way he was greeted by them on arrival with hugs and fussing, Jack's mother and both his sisters already know Mac and bear a great deal of fondness for him.

Conclusion: Mac is Cousin Jack's son, and for whatever reason, they didn't know about him until now.

The equation is not a complicated one, and word spreads pretty quickly. For the most part, nobody bats an eye. Sometimes, someone has a kid nobody knows about until the kid is a fully realized, nearly six foot tall, moderately awkward blond genius who smiles like he's worried he's offended someone and calls everyone 'sir' and 'ma'am'. The kids love him instantly, just as much as they love Jack, and as long as he's willing to entertain a small crowd of elementary schoolers by making things (tamely and in a controlled fashion) catch on fire, he'll remain a favorite of the older cousins, for sure.

As to the exact nature of how Mac _happened_ , there are a few guesses. One theory has him the son of an army buddy of Jack's who was killed in combat, leaving Jack, in all his big-hearted tendency towards altruism, to take in his near-grown child. Another speculates that maybe Jack had started dating someone and grown close enough with the woman's son to stay in his life after they split. The most likely scenario, and the one the consensus has fallen on, is that at some point very early in his twenties, Jack had a fling that resulted in a child he was uninformed of, until the kid got old enough to hunt his father down on his own, and here we are.

Where Mac's mother might be now, and why he's only ever heard referring to his father by his first name, well, they quietly chalk that up to 'probably a sore subject and not our place to ask about' and mind their own business. The Dalton family may be well versed in the art of creative theorizing, but they're not going to be rude about it, under threat of the wrath of Great-Aunt Lynette or otherwise.

And thus it is assimilated into the general understanding of the extended Dalton family that Jack has a surprise grown child who's really quite a sweet boy all things considered, and life goes on.

Mac, completely unaware of the solid third to half of his partner's family under the impression that he is related to them, has independently come to his own conclusion, and that conclusion is that the Daltons are an odd bunch. Texans at large are… unique, sure, but there's something about this specific group of people and their dogged desire to act as if they've known him his whole life that Mac finds both extremely off-putting and incredibly endearing.

It's been five years of family reunions now, five years of being brought along to the old family ranch, passed around rooms seemingly full of endless people all hellbent on hugging him to death. Five years of Jack's mother, Theresa, calling him 'baby' and directing him around the kitchen when he steps in to get away from the crowd by helping her and one of Jack's uncles cook. Five years of a pre-schooler or two per year cheerfully referring to him as their cousin, prompting Mac to smile indulgently and nod. ( _There's… a lot of cousins_ , he reasons, _and I guess when you're four it's hard to keep track._ )

Year five arrives and this time, Jack doesn't even invite him, just informs him that the reunion is coming up, and Theresa will pick them up from the airport when they get in. Mac finds himself genuinely looking forward to it, almost as if it was his own family he was about to reconnect with, a mental Rolodex of people he wants to say hello to and get updates on flipping through his brain. He thinks maybe this is what having a family you enjoy seeing feels like - looking forward to hearing about who got into what college, seeing new baby pictures, seeing who's made a terrible hairstyle and or beard decision this year.

The Daltons have always made it so easy to forget that they aren't his family. They make it so easy, everyone reacting to him the same way they react to a slew of cousins around his age, and after about the third year, Mac gave up waiting for them to realize he isn't actually one of them, and started enjoying it.

He periodically finds himself smiling on the plane on the way from California to Texas, and can't quite identify a specific reason why.

The house is warm and inviting. Theresa Dalton had hugged him just as hard as she'd hugged Jack at the airport, and the same is repeated then, Jack's two sisters as well as his brother and sister in law welcoming him with tight embraces and exclamations on how they both look tired. Nieces and nephews are on Jack immediately, taking him down in a coordinated tackling effort that leaves a highly trained Delta operative on his back on the carpet, dramatically groaning about how he's down, they got him, " _Mac_ , buddy, are you just gonna stand there?"

"Honestly, I don't know how you put up with him," Theresa remarks to Mac, eyes twinkling with mirth.

"Really, _mother_?" Jack calls dramatically from his place still pinned on the floor by a pair of giggling ten-year-olds. "This is how you talk about your only son?"

"Only when he deserves it," she calls back to him, then looks to the side and gives Mac a conspiratorial wink like the two of them know something Jack doesn't, like he's a part of her family rather than just her son's army buddy, someone who works with him and got brought home out of something not quite pity but close enough. Mac finds he quite likes being in on the joke.

Before the Annual Dalton Family Reunion begins the next day, there's always the quiet night before, with just Jack, his sisters and their families, Theresa, and Mac, milling around together after dinner, everyone tired but not ready yet to go to sleep.

There's a Dallas Stars hockey game on in the background, Jack's younger sister and one of his nephews riveted to the screen, while Jack makes the same dramatic defense he has to make every year as to how he definitely hasn't become an LA Kings fan since the last time his sister checked. Mac watches, entertained as ever by watching Jack's sisters affectionately torment him, until there's a tug on his sleeve, and he looks down to see Jack's eight year old nephew standing there.

"Mac," the boy says, voice and face innocently serious in the way only a child's can be, "we have a situation."

It's a phrase he has to have picked up from Jack, and Mac barely stifles laughter, not wanting to make the kid feel made fun of. Instead he swallows his amusement, and nods.

"What's the situation, Ben?"

"Lincoln Logs. They keep falling down," Ben Dalton says gravely, and Mac nods again.

"Show me."

Mac helps Ben and his sister fix the problems with the structural integrity of the Lincoln Log tower, an indescribable peace settling over him as he helps a pair of elementary school aged children build a tower. Jack has moved on from defending his loyalty to Texas hockey to asking after one of his favorite cousins, the son of his uncle the judge. The favored cousin doesn't seem to be coming this year, caught up with some big case at the crime lab he works for in Las Vegas, and as he listens to them talk, Lincoln Logs passed eagerly into his hands by the kids, Mac can almost imagine this is what normal feels like, what family feels like. It's a warm, contented feeling. He gets better sleep that night, in a twin bed in the second floor of a drafty old ranch house, than he has in months.

The next day dawns as bright and hectic as all Annual Dalton Family Reunions do. Somehow it always feels like there are more people each year, and everyone wants to hear about everyone else's life since the last Reunion, creating a low din of constant chatter. Mac sticks mostly to the sidelines, content to help Theresa and the newly arrived head of the family and present oldest living attendee, Great-Aunt Lynette, with the burdens of hosting. He directs people to park in the field to the side of the ranch house, helps more than one frantic child back to a lost parent, and fends off several deeply riveted older folks who've surely mistaken him for one of their _actual_ great-nephews, asking as to whether he's ever gonna bring a significant other around to meet everyone one of these days. By the time he actually joins the main fray, there are a good twenty people separating into two groups of indistinct intent.

It doesn't take long to spot Jack, joking with his uncle the judge, a welcome spot of familiarity in the mess. Mac takes a step to follow his partner, but someone he's pretty sure is Jack's aunt's son catches him halfway there, spinning him around by the shoulders and pointing him to a crowd of people who skew significantly younger than the group Jack stands with. He's propelled over to them with a light, friendly push, the Dalton cousin behind him saying, "You're over there, junior."

Mac walks over slowly, shooting bewildered looks behind him at the crowd of people gathering near Jack.

"We're playing family reunion football," the young woman now standing next to him explains. "It's adults against kids and you're with us."

"Oh. I mean. I'm…" Mac squints at her. He can't possibly look _that_ young. "I'm definitely an adult."

"Dude," she sighs, only looking about half as exasperated as she sounds, "I'm twenty-six. I graduated from NYU Law School last year, and I'm _still_ on the kids team. You're stuck with us. C'mon, though, adults have won the last three years and I'm startin' to hold a grudge."

The adults win again, but it's not for lack of a good fight. Mac makes a solemn pact with the NYU Law cousin that they'll get their comeuppance next year.

It's not the strangest interaction he's had or will have that day.

"Hey, you! Jack's boy, what's your name, over here!"

'Jack's boy', it's something he's been called with a moderate degree of regularity by a fair range of people including Jack himself, enough that he immediately responds. Mac looks over at the young woman waving, and makes the universal face and hand motion for 'do you mean me?' She nods.

"Board game tournament, we need you for our team, it's Scrabble and you're our secret weapon. You in?"

Unable to call up her name to save his life, and only vaguely sure he's ever met her before, Mac nevertheless nods, jogging over to join the small crowd of young people beginning to gather around a picnic table piled with Scrabble, Mancala, Sorry!, and a number of other old games that must have lived in Theresa's basement for more than a decade. There's a small cheer when he gets there, the girl about his age whose name he still doesn't know slinging an arm around his shoulders and announcing, "See, y'all are going _down_!"

More than an hour passes before Mac realizes he's lost track of where Jack is, and feels no less a part of things for it.

In the end, it breaks in the most anticlimactic way it could have, with a thoughtless comment from a cousin Jack sees at reunions but otherwise isn't especially close with.

Shelly Dalton has been taking her boyfriend of several months, Richard, around to meet everybody, which is a lofty goal, in Jack's opinion. The true litmus test, really, of any potential in-law of the Dalton family is how many relatives they could stand to be introduced to before they completely lost their mind. It seemed like Richard is doing well, so far, given he smiles gamely and shakes the offered hand when Shelly brings him over to where Jack stands. Shelly waves between the two of them, already peering out over to the rest of the gathered clan as she absently makes introductions.

"Jack, this is Richard. Now Richard, this is my cousin Jack, he's my aunt Theresa's middle boy, you've already met his sisters, and his son's around here someplace. You'll meet him later, I'm sure."

Richard nods, only looking vaguely overwhelmed, meanwhile Jack chokes on his tea. When he's done coughing, he straightens back up and stares at Shelly and Richard, absolutely positive there's no way he heard them correctly, and says, "Excuse me, my _who_?"

"Your son," Shelly repeats. His cousin is blinking at him like he's lost his mind. "Y'know? Mac? Bout yay tall, makes shapes out of wire, fixed Kirsten's bike with, like, duct tape and a broom handle last year?"

"My son," Jack says back to her. "My son, _Mac_."

"Ye-ah." She squints at him oddly, then looks at her boyfriend, clapping him on the shoulder. "Okay, Rich, looks like my dad might've spiked the tea again, we should go talk to him about that."

And before Jack can say anything else, or make any progress in processing what she's said, Shelly and Richard have both taken off, and he's left alone with a glass of decidedly not alcoholic iced tea and no idea what's just happened. So, as one always does when there's something going on and details are needed, once he's gotten his bearings somewhat back about him, Jack sets off to find the keeper of all Dalton family gossip.

Great-Aunt Lynette is sitting in the shade watching the goings on with the vague satisfaction of a matriarch when Jack finds her. He sits down on the chair set up next to hers, wordlessly swirling sweet tea around in his glass. The condensation beading on the side of the glass is making his palm clammy, so he sets it down for a moment, swiping his hand down the thigh of his jeans, then picks it back up again.

"Something wrong with the tea?" asks Lynette, in a tone implying that if there is something wrong with the tea, Jack ought to keep it to himself.

Jack moves right past the tea entirely, staring at it like it holds the secrets to the universe as he says, voice a hair past calm, "Apparently I have a kid, did you know I have a kid? Cause nobody told _me_ that I had a kid."

"Ah," the old woman sighs, the wisdom of eighty-four Texas summers behind the sound. "Now who was it, Shelly or Lyle?"

"What?" Jack looks over at her, sure his face is as bewildered as his voice sounds.

"I told 'em all not to go making a fuss about that boy, now which one was it that did? Had to be one 'a those two. Was it Shelly?"

Numbly, Jack nods and Lynette clucks her tongue.

"I love that child, Lord knows I do, but _subtle_ was never her middle name. What'd she say to you? Please tell me she didn't say nothin' to him about it. What'd she ask?"

Once again, Jack bypasses the question she's asked for a much more pressing point, redirecting with a question of his own.

"You _knew_ about this? You _knew_ they thought Mac was my son?" Saying it out loud feels odd, reminds Jack all over again that he can't believe he's having this conversation. It's not the first time someone's made this same assumption, but those had all been strangers, a few medical professionals, a few people they'd met on missions, one of Jack's neighbors. The idea that someone in his family, nevermind evidently more than one person in his family, has come under this impression and held it for _years_ has thrown Jack for a loop.

Even more than that, is the disquieting realization that he doesn't want to go around refuting it. The idea of making the rounds of cousins making it clear that Mac is not his child, having to disavow out loud that he's Mac's father, it makes something sick and heavy settle in his gut. He doesn't want to effectively disown Mac, especially not where the kid might hear about it.

The fact of the matter is, it's been a long time since Jack would have been able to say 'he isn't my son' and completely mean it. It's been a long time since he gave up trying to lie to himself, say he hasn't in some way cast himself in the role of parent, thought of and treated Mac more like his kid than just his partner. It's not something he's ever verbally acknowledged or pushed Mac into talking about, but it's there, and he can't imagine telling his extended family he isn't Mac's father and have it feel like anything but a lie.

"Of course I knew," Lynette scoffs, reminding Jack that there is in fact another person participating in this conversation, witnessing the absolute reeling bafflement he's currently experiencing. "Nothing goes on around here that I don't know about. Which is why I told them they better keep their mouths shut and treat that boy just as respectful as they do your sisters' families. You brought him to us, he ought to be here without worrying about nosy questions from hopeless gossips."

Jack drops his head into the hand not holding his tea, pressing hard against his eyes. Still hunched over, voice muffled, he says, "And how is it y'all think I just showed up here with a grown boy and his mother nowhere to speak of?"

"Anybody's guess," Lynette says airily. "Most everybody assumes he was an accident you didn't find out about until too late to bring him 'round any sooner than you did. Figures his momma just didn't tell you, which is why nobody asks about her. Probably a sore subject, and they know they answer to me if they go asking him or you any questions that'd make a hard situation any worse."

The way she says it leaves Jack with the distinct impression that she had perhaps engineered this not so much because she believed Jack had a son he didn't find out about for two decades and didn't want any awkward questions, but because she knew there was no blood between them and wanted to prevent thirty different people asking Jack who Mac was and why he was there. He'd believe it. If anyone would conduct a five year con in order to keep a boy brought to their family from being made to feel like he didn't belong there with a bunch of questions about who he was, it'd be Lynette Dalton.

"How long'd it take you to figure it out? That he…" Jack's voice stops on 'that he's not mine', unable to finish that sentence. She figures out what he's asking anyway.

"The day I first met him." At his confused look, Lynette elaborates. "Oh come on, Jackie. I know you, I've known you since the day you were born, and I know what kind of father you'd make. And it's not the kind of father that'd raise a boy like that."

"Aunt Lyn-" He doesn't even finish her name, spoken in a defensively warning tone, a tone he never takes with the elders of his family, the matriarchs and patriarchs he respects so much.

"Now let me finish," Lynette chides gently, eyes shining with warmth. Jack feels embarrassed immediately, but it's not like he could help it. So sue him if he's a little protective of the kid - somebody has to be. "I _mean_ the way he walks around here with that awful wanting look when he thinks no one's payin' attention, lookin' at this family like it's something he wants but can't have. No boy that _knew_ he was yours would walk around with a look like that. You couldn't raise a boy who'd ever for a moment think of questioning his place in this family. No, that damage was done long before you found him."

As shrewd as ever, Great-Aunt Lynette Dalton. Jack nods slowly, chest and throat aching in a low, bruised throb he's grown accustomed to associating with Mac.

"Yeah," he says, voice hoarse. "It was."

"Well then," Lynette announces, satisfied. "We'll just have to keep on doin' what we can do to fix that, won't we?"

Jack stares at her, the depth of gratitude he feels towards his great-aunt in that moment somehow both huge and weightless. His mouth moves in soundless words, an airless 'thank you' to her. Lynette waves her hand, snorting lightly.

"Please, do you think you're the first one 'round here to bring home some child that needed a family? We Daltons been taking in strays since long before you were a thought in your momma's sweet head, Jack Wyatt. We'll keep taking care of yours."

 _We'll keep taking care of yours_ , Jack thinks. They have been taking care of Mac since the day Jack showed up with him in tow, and suddenly he's going back over five years of bringing Mac to Dalton family reunions, the way everyone's welcomed him like one of their own. Like they thought he _was_ one of their own.

"Something's still eatin' at you, Jackie, don't try and tell me it isn't. What's got you looking like that?"

"Everyone's been so good to him," Jack says slowly. He looks once more at the glass of iced tea in his hands, studying it with more scrutiny than a glass of cold sweet tea really warrants. There's a slight imperfection in the side of the glass, a tiny, barely visible crack. His thumbnail catches against it as he scratches at the surface, worrying at the defect. "They've been treating him just like one of us, just like I'd hoped they would. 'S part of why I just kept bringing him back. So he could just be around family, around people that'd treat him well, just for a couple of days a year. And I can't help but wonder if… Y'know, if…"

"If we were only takin' such good care of him 'cause we thought you were his father?" Lynette guesses, and Jack gives a short, miserable nod.

To Jack's complete surprise, Lynette laughs. She tilts her head back a little, eyes squinting closed for a moment before she looks back at him, gaze soft and amused.

"No, baby, no," she tells him, head shaking slowly side to side. "He's yours and that makes him ours, it don't matter one bit where he came from or how he got here. Nobody would treat him any different if they knew."

"Oh," chokes out Jack, around the lump that's suddenly constricting his throat, making it hard to breathe much less speak.

"And now," Lynette says, bracing her hands on the arms of her chair and standing with the care and slow speed of an octogenarian, "you just gotta decide what you're gonna tell your boy about all this."

She turns to him and offers one small, delicate hand. Jack smiles, unable to get words out with any amount of surety they'll be steady when they leave, and nods. He stands under his own power but takes the hand anyway as he does, accepts the help in spirit. Once they're both up, he keeps holding it for a moment, squeezing lightly.

"And if you see Shelly…" Lynette says, a warning in her voice, and Jack can't help but laugh.

The question eats at Jack later, sitting on the couch after most of the family save a few have filtered out to hotels and nearby friends' houses to retire for the night. He watches Mac work on a LEGO set with his enraptured niece and nephew on his mother's living room carpet and he wonders who those kids think Mac is.

 _And now you just gotta decide what you're gonna tell your boy about all this._

Mac is grinning at the kids, fitting pieces together without hardly glancing at the instructions, patiently guiding tiny hands when either of the six and eight year olds want to do it themselves. Mostly, they're content to watch him assemble the structure, something about dinosaurs and Jurassic Park, with wide, enchanted eyes. The low light from Jack's mother's old antique lamp casts shadows across Mac's face, and it's in these shadows that his contented happiness becomes the most clear. The corners of his eyes are wrinkled by his smile, and the valleys of darkness thrown out by his cheeks are rounded with easy, painless joy.

It's there, sitting and watching his little niece and nephew playing with Mac, likely without a clue either where he truly came from or what the adults of the family are theorizing as his probable origin, delighted by him regardless, that Jack decides he can't do it. He can't tell Mac what an evidently fairly large portion of his family thinks, that there's a rumor going around that he's Jack's son. Because to tell him would mean to watch the cogs turn in his head as he frantically tried to figure out how to fix it, if he'd done something wrong, if Jack was unhappy with him. If Jack thought it was his fault the family had assumed he was one of them. How Jack felt about the assumption as a whole, if he was offended or annoyed or put off by being thought someone's dad, nevermind _Mac's_.

The information itself won't hurt him. If anything, it's funny, the conclusions drawn, the way the Daltons had tried to be so gentle and sensitive about it, treat him just like he'd grown up with them. It's endearing and amusing, and the fact of the assumption itself won't hurt. What will hurt is what Mac will do to himself with it, how he'll laugh for a second before his giant brain will start churning, going places Jack doesn't want him to go.

Best to say nothing at all, and deal with it if and when it comes up.

The next day, as cousins and aunts and uncles and significant others filter back to the old ranch land, Jack finds himself with the opportunity to do just that.

Fairly early on the day, the generator goes out. This alarms Theresa greatly, at least until Mac volunteers to go down and see what he can do, accompanied by Jack's oldest sister, Angela, who works as a contractor and tentatively knows her way around that sort of thing. Shortly after they've descended into the cellar against a backdrop of Jack's other sister and her wife telling the story of the time Jack's uncle broke three ribs falling down the cellar stairs, while Theresa informs them that _girls, that isn't helping_ , another car full of cousins arrives. With them comes the latest new girlfriend, on her first visit to a Dalton family function and thus completely unfamiliar with just about everyone present.

Hellos and how's-it-goings and name exchanges begin immediately, and right away, Jack call tell this is not going to go nearly as well as it had with Cousin Shelly's boyfriend Richard. The girl looks a little pale by the time the third person has given her a name she's sure not to remember. Jack tries to smile at her reassuringly when she's escorted past him by the overzealous boyfriend, a cousin Jack can't place his degrees of separation from. He watches the goings on from his place next to his mother, the two of them exchanging amused glances, until the back door opens and footsteps on old wood planks herald the return of Mac and Jack's sister.

"Good news, we got the generator running," Mac announces, hopping down off the back porch with Angela right behind him, just as the bewildered girlfriend has finally been introduced to the last person standing around the yard. She looks at him, at the way those around are thanking him, pats on the back and one nearby uncle ruffling his hair.

"Don't look at me," Angela says when her sister tries to congratulate her on a job well done, "it was all the kid." Mac blushes and stares down at the ground, looks like he's about to speak when Jack's cousin's girlfriend beats him to the punch.

"And how do you fit into all of this?" she asks, voice just a touch too loud and a touch too shrill, obviously overwhelmed with the number of people she's just made the acquaintance of. One more was evidently the breaking point.

Jack looks from the poor frazzled girl, to his suddenly owl-eyed partner, who seems to be frozen completely speechless by the question, and smiles. His hand claps down on Mac's shoulder, fingers curling over the fabric of his shirt and squeezing. Mac shifts almost imperceptibly closer, and Jack tightens his grip in response, a wordless _it's okay, I got this._

"That's easy. This one's mine."


End file.
